Folate malnutrition, a major cause of nutritional anemia, is the commonest vitamin deficiency in this country in relation to pregnancy, intestinal disease, certain malignancies, alcoholism, and in patients taking selected medication. The goal of this research is to continue an investigation of mechanisms of folate absorption and utilization and to evaluate mechanisms of folate deficiency in pregnant women, in patients with intestinal disease, and in patients on drugs. The technology to be used will depend on chemical and biological synthesis of radioactive and deuterium labeled monoglutamyl and polyglutamyl folates by techniques developed in this laboratory. Quantitative tests of folate absortion in patients with disease will be based on urinary excretion techniques previously reported. Stable isotope (deuterium) labeled folates will be utilized for studies of folate absorption and utilization in preganancy and in children where the use of radioisotope labeled study compounds is inappropriate or contraindicated. Deuterium labeled folates will aid in the determination of folate pool size and turnover in addition to providing data on absorption. Intestinal perfusion experiments in patients and laboratory animals will aid in elucidating the events in folate absorption. Analysis of the enzymology of folate utilization will depend on enzyme purification techniques including affinity chromatography and conventional methods with chromatographic identification and kinetic analysis of product appearance. Effects of disease and drugs on intestinal deconjugation of polyglutamyl folates will be studied in vivo using labeled synthetic folates and in vitro using preparations of enzymes from intestinal mucosa. The impact of drugs on binding and transport of folate in serum will be studied by in vivo and in vitro assays of protein-ligand binding using radioactive folates.